THE truly terrible, “Lock ‘N Load,” a six-parter debuting tonight on Showtime, is possibly the worst-taste reality series since “The Littlest Groom” — and it took some serious doing on the part of Showtime to manage that.

“Lock ‘N Load” centers around the real life doings in a Colorado gun shop whose salesman, Josh Ryan, created the show. He’s an actor/gun enthusiast who “works” there — even though he really doesn’t. Got it? Neither do I.

Anyway, there are 12 small segments in each torturously long 30-minute episode, in which Josh mugs for the camera and sells guns to the “fun” characters who drop in to buy assault weapons and talk guns, like the 8-year-old boy who really loves the Glock 17.

While the show is apolitical and doesn’t make a case for or against gun ownership, Showtime did have the mind-bogglingly bad taste to allow the show to be filmed in a shop in Denver which is (I swear, I looked it up) 10miles from Columbine High School. I mean, has everyone lost their minds here?

Yes.

In one segment, when a fat young guy comes in and Josh asks him why he doesn’t have cash to buy a gun, Lardo says, “I don’t have a job yet,” to which fun-loving Josh quips, “That’s why you need a gun!” Hey — armed robbery is always funny.

Josh hands another guy a giant assault rifle, and pitches it as, “This one’s for the mall!” What?

Finally, there’s the gun buyer who gives this marriage advice while checking out pistols: “The fastest way to a woman’s heart is with a scalpel,” while making stabbing motions. Seems a damned waste then to waste his money on a gun. Disgusting on every level.